The most commonly used measure of ingestion is the volume consumed in a fixed period of time. It is clear that this measure is inadequate if one is interested in the reason a particular amount is ingested since this amount is determined by a variety of variables. A better understanding of how these variables determine consumption can be achieved by studying the individual behavioral components, the microstructure of ingestion. The goal of the research proposed here is to understand how some of the variables know to affect the amount ingested affect individual components of the behavior that constitute an ingestive episode. This information should provide better insights concerning the nature of the central organization of ingestive behavior than can be achieved by simply measuring amount ingested. The effects of adulteration of sucrose solutions by quinine and citric acid, the dilution of sucrose and the effects of food and water deprivation on the microstructure will be studied. The changes in the microstructure of ingestive behavior of rats ingesting sucrose following the development of a conditioned taste aversion using four different US's will be measured. The sham feeding techniques is assumed to open the major negative feedback in the ingestive control system yet intake increases with experience in sham feeding suggesting the existence of an additional labile feedback loop. Experiments are planned to determine the reasons for this progressive increase and to study the microstructural changes that accompany it. The microstructural changes that accompany decreased intake induced by cholecystokinin and bombesin will be measured in sham feeding rats and these changes will be compared to those changes induced by the treatments described above in an attempt to understand the reasons for the anorectic properties of these peptides. This research will provide basic information about the microstructural changes in ingestive behavior induced by experimental alterations in volumetric intake. Since human ingestive behavior has some of the sam microstructural features which have been demonstrated in the rat the information provided by this research program should help to provide a better understanding of the nature of the various types of anorexias induced experimentally by drugs and occurring naturally in the form of anorexia nervosa.